Winding systems in which a core, sleeve or tube serves to wind up a roll or coil of a web, especially a synthetic resin web, are of course known. In the framework of the present invention, the term "contact winding" will be used to refer to a winding system in which a contact roller directly bears upon the roll and exercises a predetermined contact pressure thereon so that, as the web is wound on the roll, a certain flattening pressure is applied to the foil.
The contact roller is, therefore a counterroller which is juxtaposed with the roll. The invention recognizes a rolling system in which the counterroller is spaced somewhat from the roll by a gap in so-called "gap rolling". In that case, the counterroller may be in contact with the web but is spaced from the roll by a predetermined gap width, the web being fed to the roll through the gap.
Of course such winding systems can include other auxiliary equipment or devices which may not be described in greater detail hereinafter but are customarily provided as winding systems are present. For example, the system can include a device for feeding the winding tubes to the apparatus, guide rollers or the like for guiding the web to the roll, transverse separating means for cutting the web when a wound roll is full and before a free end of the web is to be delivered to a new winding tube, and, of course, means for transporting away the completed roll.
It is not uncommon in such winding systems to mount the counterroller on a slide means, i.e. to journal the counterroller in bearings supported by a pair of slides on opposite ends of the counterroller. The slides may be moved by two parallel slider pneumatic cylinders. For these cylinders to provide the pressing force they must be capable of following the winding operation over the full diameter of the finished roll. In that case, the cylinders must have a comparatively large stroke. Such cylinders are extremely expensive and, because of limited availability and problems of accessibility of the slides and cylinder arrangements, it has been difficult in the past to realize a desired constant pressing force of the contact roller against the roll in the process of being wound, at least over the entire winding process.
In fact, when there are irregularities in the winding process and a tendency for the roll to develop irregular contours or portions which deviate from the cylindrical, the guidance and maintenance of a constant pressing force may prove to be difficult and the quality of the foil may be adversely affected.
Similar problems arise when it is essential to maintain a constant gap width in the case of gap winding, i.e. where the counterroller is to be spaced at a precise distance from the roll being wound.